In the current state of the art, the bias, scale factor and alignment of gyros and accelerometers are calibrated over temperature at the system level during a final acceptance test. A thermal model is generated and stored in the system's processor. The thermal model is used to correct the gyro output signal over temperature fluctuations. The residual error to the thermal model and instabilities over time determines the ultimate performance limits of the inertial system.
E. J. Loper and D. D. Lynch (“Hemispherical Resonator Gyro: Status Report and Test Results”, National Technical Meeting of the Institute of Navigation, 17-19 Jan., 1984 at San Diego, Calif.) disclose a method of resetting a resonator pattern angle to average out the bias drift. Hayworth (NASA TECH BRIEF Vol. 27, No. 10 for October 2003—JPL NEW TECHNOLOGY REPORT NPO-30449) discloses interchanging drive and sense pickoff electrodes with drive and sense forcer electrodes. However, this approach is subject to errors associated with misalignment of the forcer and pickoff electrodes.